Method of adjusting well holes



May 19, 1931. A. G. H. STRAATMAN 1,806,509

METHOD OF ADJUSTING WELL HOLES I Filed Aug. 9, 1950 2 Sheets-Sheet lINVENTDFQ )7, G. Stmqtmon BY I A'T'T'CI NEV:

A. G. H. STRAATMAN 1,806,509

May 19, 1931.

METHOD OF ADJUSTING WELL HOLES Filed Aug. 9, 1930 2 Sheets-Sheet 2 :Nmu

' 1 1? G/iStracztmanv by Q fl/l J.

Patented ma re, 1931 UNITED STATES PATENT OFFICE TO NA.AMLOOZEVENOOTSCHAP DE BATAAFSCHE ZPETROLEUM MAA'ISCEAPPIJ, OE

' THE HAGUE, NETHERLANDS METHOD OF ADJUSTING WELL HOLES Applicationfiled August 9, 1930, Serial No. 474,260, and in the Netherlands June10, 1829.

- ly as possible with the vertical line. In prac- 'tical application,however, the direction of the bore-holes generally deviates from thisvertical and this invention provides a method and means whereby such adeviating hole can be brought back to the desired vertical direction.

It is known that by means of a whipstock a drill hole can be given adeviation from its original direction. There were, however, up to thisdate no practically useful method and means known to give this whipstocksuch a position as to force a slanting hole back into the normal orvertical line. Now this method and means are provided by the invention,which in principle consists in the orientation of a whipstock withregard to a clinometer. It is explained more fully with the help of theattached drawing, but is not at all restricted to the special form ofembodiment here selected.

With these and other ob'ects in view the invention consists in using t ecombination and arrangement of partsv set forth below and shown in thedrawings, in which Figure 1 is a vert1cal cross-sectional view showingdiagrammatically the parts in osition for beginning the operation ofstra1ghtening the drilled ole. v

Figure 2 is a similar view showing the operation further advanced, and

Figure 3 shows a similar view with modified apparatus.

Figure 4 is a vertical cross-sectional view on an enlarged scale,showing some parts more in detail, and

Figure 5 is a horizontal cross-sectional tached, preferably screwedthereto. It is not necessary to determine the'position of this whipstockwith regard to the points of the compass; the point is rather to give toits symmetrical plane such a direction that it coincides with thedeviation plane of the drilled hole, which is the one over which thesectional view of Fig. 1 has been taken, in order to bring about adeviation of the bored hole in the desired direction. By deviation planeis meant a plane through the center line of the deviating bored hole ata certain place and the vertical line at such place. Furthermore, on thewhipstock itself or by the aid of a separate element means are providedto orientate the whipstock with re ard to a clinometer, e. g. an acidbottle. ince this orientation constitutes the essence of the invention,it will be explained herein more in detail.

In case the independent auxiliary element 4 shown in the drawing beemployed, which afterwards may be pulled up separately by means of agripping device, 1. e. without the tube 2, and which is provided e. g.with one or several characteristic unevennesses 7, 8 or projections,which leave an impression on the lead bottom with which the mantle ofthe acid bottle is provided, the plane of symmetry of the whipstock canbe determined in a relatively simple manner with regard to the plane ofdeviation, after which the position of the whipstock can eventually becorrected. For this determination it is necessary in the first place toknow the position of the element 4 with regard to the whipstock. Thisposition can be set when screwing or placing the whipstock and theauxiliary element on to the tube 2. Preferably this element is providedwith two difi'erent marking elements 7, 8, which leave, each, adifierent im res- S1011 (e. g. one element may be a triangu arly shapedprojecting part, the other one be a quadrangular projecting part) andwhich are arranged in a median line of thecircular auxiliary elemerrfl.This element may be screwed into the upper cylindrical extension of thewhipstock by means of left-handed screw-thread, as shown in Fig. 4.

The median line of the element 4, provided with the marks 7, 8 is, whenthe apparatus is mounted in the tube 2, made to coincide with rangularshape on said bottom, indicating a median line of this bottom, which islying in the symmetrical plane of the whipstock. The acid within thebottle etches that part of the inner wall of it, which is situatedbeneath the liquid level, so that an elliptical line on this cylindricalinner wall between the etched and the non-etched part afterwardsindicates the surface of the acid. As will be obvious, the longer axisof the ellipse will be situated in the deviation plane of the bore hole.

After the acid bottle has been pulled up to the ground surface, itclearly indicates the relative position of symmetrical plane ofwhipstock and deviation plane of bore hole, this position being the sameas that of the median planes of the bottle over the marks and over thelonger axis of the ellipse respectively. If the whipstock is well set,i. e. if its plane of symmetry coincides with the plane of deviation,the line running over the two impressions of the characteristicprojecting parts and the longer axis of the ellipse, along which thesurface of the acid is marked on the inner wall of the bottle betweenthe etched and the non-etched part, lie in the same median plane of theacid bottle. Moreover the impression of the marking element situatednearest to the whipstock must be on that side of the longer axis of theellipse which is nearest to the bottom of the acid bottle. If this isnot the case, then the angle between the plane of symmetry and the planeof deviation is the angle between the median planes containing themarked center line and the longer axis of the ellipse respectively, sothat the proper correction in the position of the whipstock can be madeimmediately by raising the tube 2 and displacing it by the desiredangle. Then the auxiliary element is pulled up, which may be done byinserting a string of rods provided at its lower end with ascrew-threaded head corresponding to the screw-threaded central hole ofthe element 4. After screwing the head into this hole, continuedrotation of the string will unscrew the element 4 on account of itsleft-handed screw-thread, with which it is provided at its periphery.After taking away the auxiliary element a drilling chisel correspondingin size to the space between the whipstock and the opposite drill-holewall is inserted and lowered. This chisel will assume a direction whichdiffers from that of the preceding drilling and especially will morenearly coincide with the vertical line than the former (Fig. 2). Thebore-hole is then brought to the desired size in thecustomary way bymeans of a second drill or reamer, which follows the already drilledsmaller hole. Generally the obtained change of direction will be small,which with regard to the introduction of the casing is desirable.

By a periodical repetition of the described process the bore-hole can,after a certain deptl has been drilled, be brought as near to thevertical line as may be desired, or may be made to coincide with italtogether.

The whipstock serves only for guiding a relatively small drill, wherebythe same can be damaged only slightly.

It is evident that the described process may be altered in various wayswithout deviating from the principle of the invention. As has alreadybeen observed, any suitable clinometer may be used, provided it can beorientated according to the principle of the invention with regard tothe whipstock. Also the method of orientation itself may varyconsiderably, and e. g. instead of the described auxiliary element 4 anyother element may be used, which can serve for indi cating the positionof the plane of symmetry of the whipstock. The whipstock may even beorientated without the help of an intermediate el'ement directly by theclinometer, although in practice the use of the same will be preferred,since all parts necessary for the orientation may then be easily removedfrom the drill-hole. Finally, after setting the whipstock it is possibleto continue drilling in a different way without deviating from theprinciple on which the invention is based.

As an example in Fig. 3 a method is represented where the chisel ordrill is fastened to a special boring rod 5, which rotates in acylindrical guide-piece 6, which may become wedged between the whipstockand the wall of the drill hole, whereby the damages to the whipstock maybe restricted to a minimum.

Finally also the method may be employed where with a slantingdrill-holehaving a casing the casing tube has to be drilled through at acertain place and the drilling has to be continued from here in adifferent direction.

' I claim:

1. Process for orientating a whipstock in i a slanting bore hole to bedeflected into a vertical direction, which comprises inserting in thebore hole a series of tubes provided at its lower end with a whipstock,recording the position of the plane of symmetry of the '5 1 whipstockwith regard to the deviation plane of the bore hole by means of aclinometer device and shifting the position of the whipstock bydisplacing its tubes by the desired angle in accordance with the recordobtained.

2. Apparatus for orientating a whipstock comprising a whipstockconnected to the lower end of a series of tubes and provided with aremovable element for indicating the plane of symmetry of the whipstockand adapted to make an indication mark upon a clinometer device.

3. Apparatus according to claim 2 in which the removable element of thewhipstOCk is provided with two projecting arts situated in the plane ofsymmetry 0 the whipstock and in a line perpendicular to the axis of thetubes carrying the whipstock, said projections being adapted to make differently shaped impressions into a relatively soft surface, such as inthe'bottom of a clinometer device.

In testimony whereof I have signed my name to this specification.

ALPHONS GERARD HUBERT STRAATMAN.

